Aux 1 Unit 3 Q6

1 / 10

What is the primary function of a globe-type screw lift valve in a seawater service system?

B) To prevent the backflow of seawater

D) To filter debris from seawater

A) To regulate the flow of seawater

C) To mix seawater with freshwater

2 / 10

What is the role of the bonnet in a globe-type screw lift valve?

A) To direct the flow of seawater

C) To filter debris from the seawater

B) To house and protect the internal components, such as the stem and disc

D) To regulate the temperature of the seawater

3 / 10

How does the flow path in a globe-type screw lift valve typically differ from that in a gate valve?

D) The flow path in a globe valve is circular, improving flow efficiency

B) The flow path in a globe valve is S-shaped, providing better throttling capabilities

A) The flow path in a globe valve is straight, while in a gate valve, it is S-shaped

C) The flow path in a globe valve is direct, minimizing pressure drop

4 / 10

What component of the globe-type screw lift valve moves to control the flow of seawater?

C) The disc (or plug)

B) The handwheel

A) The valve body

D) The bonnet

5 / 10

What is a key advantage of using a globe-type screw lift valve in seawater service compared to other valve types?

D) It requires no maintenance

B) It provides precise control over flow rates

A) It offers quick on/off operation

C) It is less expensive than other valve types

6 / 10

Which material is most commonly used for the valve body of a globe-type screw lift valve in seawater service, and why?

C) Cast iron, because it is inexpensive

A) Brass, because it is lightweight

B) Stainless steel, because it is corrosion-resistant

D) Aluminum, because it is easy to machine

7 / 10

How is the disc in a globe-type screw lift valve operated to control the flow of seawater?

D) By a temperature-sensitive actuator

A) By an automated control system

B) By manually turning a handwheel, which raises or lowers the disc via the stem

C) By a pressure differential across the valve

8 / 10

Which material is typically used for the valve seat in a globe-type screw lift valve used for seawater service, and why?

C) Plastic, because it is lightweight and inexpensive

B) Bronze, because it is durable and resistant to seawater corrosion

D) Aluminum, because it has good thermal conductivity

A) Rubber, because it provides a flexible seal

9 / 10

Why is it important for the valve stem in a globe-type screw lift valve to be made from a corrosion-resistant material?

C) To ensure the valve remains aesthetically pleasing

D) To improve the valve's ability to handle high pressure

B) To prevent the stem from seizing or corroding in a seawater environment

A) To reduce the overall weight of the valve

10 / 10

In a globe-type screw lift valve, what ensures a tight seal when the valve is closed?

B) The design of the disc and valve seat

C) The thickness of the valve body

A) The stem's material

D) The size of the handwheel

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